Be lazier when loading KeyFunctions from PCH/modules. We don't need to load

these in eagerly if we're not actually processing a translation unit. The added
laziness here also avoids us loading in parts of a CXXRecordDecl earlier than an
upcoming class template specialization merging patch would like.

Ideally, we should mark the vtable as used when we see a definition for the key
function, rather than having a separate pass over dynamic classes at the end of
the TU. The existing approach is pretty bad for PCH/modules, since it forcibly
loads the declarations of all key functions in all imported modules, whether or
not those key functions are defined.

llvm-svn: 189627

1 files changed, 11 insertions, 12 deletions

diff --git a/clang/lib/AST/RecordLayoutBuilder.cpp b/clang/lib/AST/RecordLayoutBuilder.cpp
index 5df372639da..e5222c971e3 100644
--- a/clang/lib/AST/RecordLayoutBuilder.cpp
+++ b/clang/lib/AST/RecordLayoutBuilder.cpp
@@ -2438,32 +2438,31 @@ const CXXMethodDecl *ASTContext::getCurrentKeyFunction(const CXXRecordDecl *RD)
   assert(RD->getDefinition() && "Cannot get key function for forward decl!");
   RD = cast<CXXRecordDecl>(RD->getDefinition());
 
-  const CXXMethodDecl *&entry = KeyFunctions[RD];
-  if (!entry) {
-    entry = computeKeyFunction(*this, RD);
-  }
+  LazyDeclPtr &Entry = KeyFunctions[RD];
+  if (!Entry)
+    Entry = const_cast<CXXMethodDecl*>(computeKeyFunction(*this, RD));
 
-  return entry;
+  return cast_or_null<CXXMethodDecl>(Entry.get(getExternalSource()));
 }
 
-void ASTContext::setNonKeyFunction(const CXXMethodDecl *method) {
-  assert(method == method->getFirstDeclaration() &&
+void ASTContext::setNonKeyFunction(const CXXMethodDecl *Method) {
+  assert(Method == Method->getFirstDeclaration() &&
          "not working with method declaration from class definition");
 
   // Look up the cache entry.  Since we're working with the first
   // declaration, its parent must be the class definition, which is
   // the correct key for the KeyFunctions hash.
-  llvm::DenseMap<const CXXRecordDecl*, const CXXMethodDecl*>::iterator
-    i = KeyFunctions.find(method->getParent());
+  llvm::DenseMap<const CXXRecordDecl*, LazyDeclPtr>::iterator
+    I = KeyFunctions.find(Method->getParent());
 
   // If it's not cached, there's nothing to do.
-  if (i == KeyFunctions.end()) return;
+  if (I == KeyFunctions.end()) return;
 
   // If it is cached, check whether it's the target method, and if so,
   // remove it from the cache.
-  if (i->second == method) {
+  if (I->second.get(getExternalSource()) == Method) {
     // FIXME: remember that we did this for module / chained PCH state?
-    KeyFunctions.erase(i);
+    KeyFunctions.erase(I);
   }
 }